If I deploy a WAR file while Tomcat is running, is there a way to load (or reload) it without restarting Tomcat?

If you are using Tomcat 4, you can reload, start or stop a particular
context through "Tomcat Manager Application". The available commands
for the Manager application are:

http://localhost:8080/manager/install?path=/xxx&war=yyy -
Install the web application whose WAR file (or directory
containing the unpacked application) is present at URL yyy,
and attach it to context path /xxx. See below for valid syntax
options for the web applcation archive URl. If the URL of an actual
WAR file is specified, the WAR will be automatically expanded
into a directory underneath the application base for this virtual host.
http://localhost:8080/manager/list - List the context paths of all currently
installed web applications for this virtual host. Each context will be
listed with the following format path:status:sessions. Where path is
the context path. Status is either running or stopped. Sessions is
the number of active Sessions.
http://localhost:8080/manager/reload?path=/xxx - Cause the web application
installed at context path /xxx to reload all its associated Java
classes, even if automatic reloading is disabled.
http://localhost:8080/manager/remove?path=/xxx - Cause the web application
installed at context path /xxx to be gracefully shutdown and
delete the web application directory and files.
http://localhost:8080/manager/sessions?path=/xxx - List session information
about the web application attached to context path /xxx for this
virtual host.
http://localhost:8080/manager/start?path=/xxx - Start the web application
attached to context path /xxx for this virtual host.
http://localhost:8080/manager/stop?path=/xxx - Stop the web application attached
to context path /xxx for this virtual host.